Check this mod out. The final version of The Delta Sector modification for FarCry has been released. This mod features three singleplayer missions, a multiplayer mode and has dramatically improved graphics. More info and link to downloads over here.
You are a member of a special forces team. It's your job to check what's happen in eastern europe, because many military forces accumulate in one area. In the later game, you find out that the others examine an old alien space ship from earlier space invaders which is bury in the deep earth.